About

This utility transforms binary image data into a Base64 ASCII string, commonly known as a Data URI. By embedding image data directly into HTML, CSS, or JSON, developers can reduce the number of HTTP requests required to load a page, potentially improving First Contentful Paint (FCP) times for small assets like icons, logos, and placeholders.

However, Base64 encoding is not without cost. The encoding process typically results in a file size increase of approximately 33% compared to the original binary. This tool calculates the exact inflation ratio and provides strict warnings for files exceeding recommended thresholds (typically 15KB for icons or 1MB for critical images), ensuring you do not inadvertently degrade performance while attempting to optimize it.

Formulas

Base64 encoding maps binary data to a set of 64 ASCII characters. The file size increase is deterministic. For every 3 bytes of binary input, 4 bytes of ASCII output are generated.

{

S_output ≈ 43 × S_inputInflation = 33.3%

The exact length of the resulting string, including padding characters (=), can be calculated as:

4 × n3

Where n is the length of the input in bytes, rounded up to the nearest multiple of 3.

Reference Data

Format	MIME Type	Typical Use Case	Browser Support
JPEG	image/jpeg	Photographs, High-color images	100%
PNG	image/png	Transparent logos, Icons, UI elements	100%
WebP	image/webp	Modern compression, versatile	97%+
SVG	image/svg+xml	Vector graphics, Icons	100%
GIF	image/gif	Simple animations	100%
AVIF	image/avif	Next-gen compression (High efficiency)	85%+
ICO	image/x-icon	Favicons	100%
BMP	image/bmp	Legacy (Avoid in web)	Limited

Frequently Asked Questions

Base64 uses 6 bits to represent a character, whereas a byte uses 8 bits. To represent 3 bytes (24 bits) of data, Base64 requires 4 characters (4 x 6 = 24 bits). This 4:3 ratio results in a strictly mathematical 33% increase in size, plus a small overhead for the Data URI header.

Use Base64 for very small assets (icons, tiny patterns, spacers) under 10-15KB to save an HTTP round-trip. Do NOT use it for large hero images or galleries, as it increases the HTML/CSS parse time, blocks the main thread during decoding, and prevents the image from being cached separately by the browser.

Generally, Google can index Data URI images, but standard <img src='file.jpg'> is preferred for Image Search optimization. Data URIs are best used for decorative UI elements (CSS backgrounds) rather than content images.

The browser may freeze. While this tool supports large files via memory optimization, generating a 13MB+ text string is computationally expensive and useless for web performance. The tool will issue a strict "Critical Size" warning for such files.